| 摘要 |
PURPOSE:To prevent reproduced beams from decreasing, and to stabilize the reproduction of information recorded on an optical card and the respective controls of tracking and focusing by providing a wavelength plate selectively arranged on the optical path between a light emitting diode and a polarized beam splitter. CONSTITUTION:The phase of a first linearly polarized component from a light emitting diode LED is changed by 90 deg. with a wavelength plate HB to be a P polarized component, and the phase of a second linearly polarized component is changed by 90 deg. with the wavelength plate HB to be an S polarized component. For this reason, the first linearly polarized component accounting for major proportion is transmitted through a polarized beam splitter PBS, and the second component acounting for the minor proportion is reflected by the polarized beam splitter PBS. Consequently the reproduced beams for an optical card RM are increased. Thus the S/N of the information reproducing signal is increased based on the reflected beams for the optical card RM, information reproducing ability is improved, and the controls of tracking and focusing are stabilized. |
